1. For soup, in large saucepan or Dutch oven cook onion in butter until tender. Stir in broth, undrained tomatoes, tomato paste, basil, thyme and the 1/4 teaspoon pepper. Bring to boiling. Reduce heat. Simmer, covered, for 15 minutes, stirring occasionally.
2. Meanwhile, for cracker topping, in small bowl stir together feta cheese, cream cheese and 1/8 teaspoon pepper. Cover and refrigerate until needed.
3. To serve, ladle soup into bowls. Spoon dollops of sour cream on top of soup (if desired). Spread feta mixture on KEEBLER CLUB Original crackers. Serve with soup.